It is common in the dispensing arts to provide disposable units in which a pump is secured to a container that holds fluid that is to be dispensed. Actuating the pump causes the fluid to be dispensed from the container, and, when the container is empty of fluid (or the fluid level is below the pump intake), the unit can be disposed of and replaced with a new unit. While a multitude of fluids are dispensed in this manner, various fluids of particular interest in the present application include soaps, sanitizers, and lotions, though this invention is not to be limited to or by any particular fluid to be dispensed.
In some dispensing systems, the combination pump and container are received in a dispenser housing, which provides the actuating mechanisms necessary to actuate the pump and cause the dispensing of fluid to the individual operating the dispensing system. An exemplary dispenser and refill unit are shown in FIGS. 1 and 2. The dispenser 10 includes a dispenser housing 12 that is mounted to a wall and opens to receive a combination reciprocating piston pump 14 and container 16, the combination being herein referred to as a “refill unit,” which is designated by the numeral 18. In the exemplary embodiment shown, a pushbar 20 of the dispenser housing 12 interacts with the reciprocating piston pump 14 of the refill unit 18 such that pushing on the pushbar 20 (typically when the cover 21 of the dispenser housing 20 is closed) causes the reciprocating piston pump 14 to be actuated to dispense fluid at the outlet of the dispenser 10. The dispenser housing and refill unit concept is all generally known and currently widely practiced in the dispensing arts, particularly for soaps, sanitizers and lotions and other personal care products.
A cross-section of a refill unit 18 is shown in FIG. 2. The reciprocating piston pump 14 fluidly communicates with a liquid S within the container 16 through inlet 22 of an axial extension 24 that extends adjacent a liquid inlet valve seat for liquid inlet valve 28. The foam pump of FIG. 2 is shown and described in U.S. Pat. No. 6,053,364, which is incorporated herein by reference in its entirety. The liquid inlet valve 28 defines in part a liquid chamber 26, the liquid chamber is defined by the volume within sidewall 50 between the inlet valve 28 and liquid outlet valve 30.
A liquid piston 32 reciprocates within the liquid chamber 26 and is biased by a spring 34 to a rest position, shown in FIG. 2, wherein the liquid chamber 26 has an expanded volume. The liquid piston 32 reciprocates back and forth to pump liquid. To dispense fluid, the liquid piston 32 is moved against the bias of the spring 34 (upwardly in the orientation of FIG. 2) to an actuated position in which the volume of the liquid chamber has been compressed. The change in volume increases the pressure within the liquid chamber 26, causing the inlet valve 28 to close off communication with the interior of the container 16 at inlet 22. The increase in pressure also causes the outlet valve 30 to open, and liquid S in liquid chamber 26 flows into mixing chamber 36. When the piston moves back downward to its rest position, the volume of liquid chamber 26 expands drawing liquid into liquid pump chamber 26 from container 16 through inlet 22.
Pump 14 includes an air chamber 38 and an air piston 40. The air piston 40 moves with the movement of the liquid piston 32 to compress the volume of the air chamber 38 which forces air from the air chamber 38 into the dispensing mixing chamber 36 where the air mixes with the liquid S to create a foam, which is dispensed out of outlet 48.
The reciprocating piston pump 14 is employed in an inverted position as shown in FIGS. 1 and 2, with the reciprocating piston pump 14 positioned partially in the neck 42 of the container 16 and held therein by an cap portion 45 threaded over the neck 42 of the container 16. The inlet 22 of the axial extension 24 extends well into the interior of the container 16, above an established floor of the container 16. As shown in FIG. 2, the reciprocating piston pump 14 might entirely fill in the neck 42, such that a floor 17 would be established at the bottom of the container 16, with the liquid S in the container 16 being able to reach that floor 17 in the inverted positioning of the container 16. Alternatively, as shown in FIG. 3, the reciprocating piston pump 14 may fit intimately in the neck 42 with its structure such that it provides a lowermost floor 29 (at the exterior sloped surface of the reciprocating piston pump 14) for the contents of the container 16. In such an instance, the pump itself would be considered as providing a floor for the liquid.
In the inverted positioning shown in FIG. 2, once the level of liquid in the container 16 falls below the inlet 22 of the axial extension 24, subsequent actuation of the reciprocating piston pump 14 will not draw liquid from the container and into the liquid chamber 26, and much of the contents of the refill unit 18 will be wasted (or at least be incapable of being dispensed by further actuation of the inverted reciprocating piston pump 14). Particularly, that volume of liquid S existing between the inlet 22 and the floor of the container 16, whether of a type like floor 17 or floor 29 described above, will not be capable of being dispensed by further actuation of the inverted reciprocating piston pump 14. This leads to a significant waste of liquid S.
This problem has been addressed in the prior art by providing either a curved dip tube 44 shown in FIG. 3 or an uptake shroud 46. In FIG. 3, a curved dip tube 44 fluidly communicates with inlet 22 and effectively provides the reciprocating piston pump 14 with an inlet 22b at a position much lower than that for inlet 22. Similarly, in FIG. 4, an uptake shroud 46 fluidly communicates with inlet 22 and effectively provides the reciprocating piston pump 14 with an inlet 22c at a position much lower than that for inlet 22. Although the intake of the valve has been lowered, a problem occurs when the refill unit begins to empty air sometimes travels up the intake shroud or extension pipe and causes inconsistent outputs. These exemplary prior art embodiments are shown and described in U.S. Pat. No. 7,641,077 titled Pump Dispensers and U.S. Pat. No. 8,591,207 titled Pump With Side Inlet Valve For Improved Functioning In An Inverted Container. Both of which are incorporated herein by reference in their entirety.